Resizing Images in VB NET

Question

I d like to make a simple VB utility to resize images using vb net  I am having trouble figuring out what vb class to use to actually manipulate the images  The Image class and the Bitmap class don t work   Any ideas  hints  tips  tutorial links are greatly appreciated   Thanks

User · Answer

You can simply use this one line code to resize your image in visual basic .net

Public Shared Function ResizeImage(ByVal InputImage As Image) As Image
        Return New Bitmap(InputImage, New Size(64, 64))
End Function

Where;

"InputImage" is the image you want to resize.
"64 X 64" is the required size you may change it as your needs i.e 32X32 etc.

User · Answer

This is basically Muhammad Saqib s answer except two diffs  1   Adds width and height function parameters  2   This is a small nuance which can be ignored    Saying  As Bitmap   instead of  As Image     As Image  does work just fine   I just prefer to match Return types   See Image VS Bitmap Class  Public Shared Function ResizeImage ByVal InputBitmap As Bitmap  width As Integer  height As Integer  As Bitmap     Return New Bitmap InputImage  New Size width  height   End Function  Ex  Dim someimage As New Bitmap  quot C  somefile quot   someimage   ResizeImage someimage 800 600

User · Answer

Dim x As Integer   0     Dim y As Integer   0     Dim k   0     Dim l   0     Dim bm As New Bitmap p1 Image      Dim om As New Bitmap p1 Image Width  p1 Image Height      Dim r  g  b As Byte     Do While x  lt  bm Width - 1         y   0         l   0         Do While y  lt  bm Height - 1             r   255 - bm GetPixel x  y  R             g   255 - bm GetPixel x  y  G             b   255 - bm GetPixel x  y  B             om SetPixel k  l  Color FromArgb r  g  b               y    3             l    1         Loop         x    3         k    1     Loop     p2 Image   om

User · Answer

Don t know much VB NET syntax but here s and idea  Dim source As New Bitmap  C  image png    Dim target As New Bitmap size Width  size Height  PixelFormat Format24bppRgb   Using graphics As Graphics   Graphics FromImage target      graphics DrawImage source  new Size 48  48    End Using

User · Answer

This will re-size any image using the best quality with support for 32bpp with alpha   The new image will have the original image centered inside the new one at the original aspect ratio    Region   ResizeImage       Public Overloads Shared Function ResizeImage SourceImage As Drawing Image  TargetWidth As Int32  TargetHeight As Int32  As Drawing Bitmap         Dim bmSource   New Drawing Bitmap SourceImage           Return ResizeImage bmSource  TargetWidth  TargetHeight      End Function      Public Overloads Shared Function ResizeImage bmSource As Drawing Bitmap  TargetWidth As Int32  TargetHeight As Int32  As Drawing Bitmap         Dim bmDest As New Drawing Bitmap TargetWidth  TargetHeight  Drawing Imaging PixelFormat Format32bppArgb           Dim nSourceAspectRatio   bmSource Width   bmSource Height         Dim nDestAspectRatio   bmDest Width   bmDest Height          Dim NewX   0         Dim NewY   0         Dim NewWidth   bmDest Width         Dim NewHeight   bmDest Height          If nDestAspectRatio   nSourceAspectRatio Then              same ratio         ElseIf nDestAspectRatio  gt  nSourceAspectRatio Then              Source is taller             NewWidth   Convert ToInt32 Math Floor nSourceAspectRatio   NewHeight               NewX   Convert ToInt32 Math Floor  bmDest Width - NewWidth    2           Else              Source is wider             NewHeight   Convert ToInt32 Math Floor  1   nSourceAspectRatio    NewWidth               NewY   Convert ToInt32 Math Floor  bmDest Height - NewHeight    2           End If          Using grDest   Drawing Graphics FromImage bmDest              With grDest                  CompositingQuality   Drawing Drawing2D CompositingQuality HighQuality                  InterpolationMode   Drawing Drawing2D InterpolationMode HighQualityBicubic                  PixelOffsetMode   Drawing Drawing2D PixelOffsetMode HighQuality                  SmoothingMode   Drawing Drawing2D SmoothingMode AntiAlias                  CompositingMode   Drawing Drawing2D CompositingMode SourceOver                   DrawImage bmSource  NewX  NewY  NewWidth  NewHeight              End With         End Using          Return bmDest     End Function  End Region

User · Answer

Here is an article with full details on how to do this   Private Sub btnScale Click ByVal sender As System Object        ByVal e As System EventArgs  Handles btnScale Click       Get the scale factor      Dim scale factor As Single   Single Parse txtScale Text         Get the source bitmap      Dim bm source As New Bitmap picSource Image         Make a bitmap for the result      Dim bm dest As New Bitmap            CInt bm source Width   scale factor             CInt bm source Height   scale factor          Make a Graphics object for the result Bitmap      Dim gr dest As Graphics   Graphics FromImage bm dest         Copy the source image into the destination bitmap      gr dest DrawImage bm source  0  0            bm dest Width   1            bm dest Height   1         Display the result      picDest Image   bm dest End Sub    Edit  One more on the similar lines

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